TAMPA, Fla. (WFLA) — If you think this summer has been unusually hot, you’re right. Two months late and one to go, it was the hottest on record.
The National Weather Service announcement that June and July were the hottest two consecutive months in the city’s recorded history. And July was the hottest month on record in Tampa. and beyond. With an average temperature of 86.3 degrees Fahrenheit at Tampa airport, the month beats its closest competitor (September 2018) by far – 0.5 degrees.
During July 10, records were either tied or broken – mostly morning lows. And it’s no coincidence, it’s part of a very robust regional trend.
So WFLA climate scientist Jeff Berardelli decided to dig into the local data. What he discovered is astonishing. 57% of Tampa’s hot morning records have occurred since 2015. Given that Tampa’s records date back 132 years, the likelihood of this remarkable statistic being chance is almost non-existent.
Since 1970, Tampa’s morning lows have risen 3.7 degrees F. That’s significantly more than the average daily temperature which has risen 1.7 degrees F.
This therefore raises the following question: why does the climate, and more particularly in the mornings, warm up so quickly? There are two answers to this.
The first involves what is known as the urban heat island effect. Simply put, urban areas tend to generate and trap more heat. The more buildings and asphalt an area has, the darker the surfaces, the more heat is trapped.
The Tampa Bay area has grown significantly over the past few decades. Since 1970 the the population has increased from about 1 million people to 3 million people. This is accompanied by a more densely built-up urban area. In Tampa, the official temperature is measured at the airport. The airport has also become more built up and therefore some of the extra heat is likely attributable to this.
On a larger scale, climate change is to blame. Summers have warmed significantly around the world and here in the United States due to increases in heat-trapping greenhouse gases.
And warmer mornings play an outsized role. In the image below, from the first half of July 2022, you can see how climate change has made the majority of warm nights at least twice as likely (and often 5 times as likely) in the southern half from the country.
So why are the nights warming up faster than the days because of climate change? There are several reasons, but the main one is the extra water vapor in the air. As temperatures warm, the air can hold more water vapour. Water vapor is itself a greenhouse gas. The extra moisture in the air traps more heat. This is especially true at night.
During the day, the sun heats the ground and surface air temperatures. At night, this heat is radiated back into space. But when there is more humidity and clouds, that heat sinks back down to the ground, keeping temperatures warm. You can think of this as having a thicker blanket.
Ultimately, as temperatures continue to warm due to human-induced climate change, we should expect these record summers to only get hotter.